The present invention relates generally to the field of control systems and in particular to a new and useful controller for a stepper-motor.
Stepper-motors are ubiquitous in modern office equipment and other machinery, and yet little is published regarding their optimal use in open loop systems. Stepper motors are a good choice for open loop applications because the position error is not cumulative with rotation as long as synchroism is maintained.
Stepper-motors and control algorithms are disclosed for simulating the performance of particular operations. For example, Leenhouts, A. C., “Step Motor System Design Handbook, 2nd Ed.”. Litchfield Engineering Co.: Kingman, Ariz. (1997) identifies algorithms for generating stepper motor step sequences and optimizing these sequences based on simulation of the stepper motor system. And, in Robrecht, M. and J. Luckel, “A Model-Based Approach to Generating an Optimized Sequence for Stepping-Motor Systems,” 7th UK Mecahntronics Forum International Conference, Georgia Inst. of Tech., Atlanta, Ga. (2000) the step sequence is extracted from a closed loop stepper-driven system and applied in open loop mode.
Accurate control of a stepper-motor is limited by the ability of the control system to approximate the actual motor and subsequently provide the correct instructions for achieving the actual desired movement, with little or no error. That is, to move a motor to a specific position in a specific amount of time, and therefore at a certain velocity, is difficult due to variations between the motor and the model. The optimal solution may change depending on the desired optimized factor, such as minimizing residual vibration, producing a quick settling time or having an accurate position and velocity trajectory. While a solution can be found, finding the desired optimal performance solution for controlling a stepper-motor is difficult and time-consuming.